Speciation in soda lake cichlids: ecological and genomic characterisation of reproductive barriers

Theme: Evolution & Adaptation

Primary Supervisor:

Julia Day

Genetics, Evolution and Environment, UCL

Project Description:

Organisms that live in extreme environments make excellent candidates for investigating adaptation to a changing environment. The unprecedented stresses experienced by aquatic organisms in the last decades make it important to determine, from an evolutionary perspective, the mechanisms enabling some species to speciate in naturally occurring adverse environments.

This project will improve our understanding of the mechanisms of evolutionary change by linking ecology and selection to phenotype and genotype. Specifically, the project examines the evolution of reproductive barriers among a recent adaptive radiation of Alcolapia soda lake cichlids, which are endemic to the small East African soda lakes Natron and Magadi that have some of the most hostile environments supporting fish life. Studying recent radiations in isolated insular systems avoids confounding possible causal events and offers clearer insight into mechanisms generating biological diversity

Surprisingly these unique cichlids have been overlooked from an evolutionary perspective. This multidisciplinary project involves behavioural experiments, molecular work, high-throughput sequencing and QTL mapping to shed light on the genomic architecture underlying the process of species formation. Captive breeding stocks of the three Natron Alcolapia species have been established in 2017 following fieldwork by Dr Julia Day and project partners, although there will be the possibility of additional fieldwork.

The project will aim to 1) evaluate total reproductive barriers between Alcolapia species; 2) test the contributions of pre- (colouration) and post-zygotic (egg sterility, viability) barriers to overall barriers; 3) test for genetic architectures expected to promote evolution of these reproductive barriers.

Policy Impact of Research:

Speciation, the formation of new species, is fundamental to understanding the generation of biodiversity. Reproductive barriers reduce or prevent interspecific hybridization, allowing closely-related species to co-occur. Understanding these barriers and their genetic basis is key to understanding how species can form in the face of gene flow between diverging taxa.


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